Known chain sprocket and sprocket drive systems include a sprocket and an inverted tooth chain assembly including at least two links. One known link is shown in FIG. 1, which shows a link according to the prior art. These known links 108 typically include two teeth 110, 112, inner flanks 118, 120, and a crotch 122. As shown in FIG. 1, the crotch surface 132 of the crotch 122 has a constant radius profile between the inner flanks 118, 120. For any given link, the center point of the crotch surface is the critical design area for supporting loads. Any given link has a high stress concentration and its lowest fatigue safety factor at this center point. Known solutions for increasing the strength of the link at this center point include either increasing the crotch depth or increasing the width of the links. Both of these solutions increase the material required to form a link and increase the mass of the link, which is undesirable. It would be desirable to provide a link that both increases the safety fatigue factor for the link, particularly at a center point of the crotch, and generally does not increase the amount of material required to form the link.